1. Field of the Invention
The present invention relates to a semiconductor package and a method of production of the same, more particularly relates to a semiconductor package superior in high frequency characteristics and a method of production of the same.
2. Description of the Related Art
In semiconductor packages handling high frequency signals of microprocessors etc., the frequency characteristics in the signal transmission path become a problem. Therefore, the practice has been to prevent reflection of signals at the input and output terminals by matching the characteristic impedance or shortening the signal line as much as possible. For example, as methods of matching the characteristic impedance, there are the method of making the signal transmission path coplanar in shape to virtually form a coaxial line, the method of providing a recess in the circuit board and inserting a coaxial cable in the recess to obtain a coaxial structure (Japanese Unexamined Patent Publication (Kokai) No. 5-167258), etc. Further, as the method of shortening the signal line, the practice has been to arrange a chip capacitor and other circuit parts as close as possible to the connection terminals of the semiconductor chip.
Summarizing the problem to be solved by the invention, if however the frequency of the signal handled by the semiconductor package becomes a high one of 1 GHz, fluctuations in the power supply will have an effect on the frequency characteristics, so the practice has been to connect a large-sized capacitor to the power supply line so as to suppress any drop in power supply voltage when a signal is transmitted. In the case of a semiconductor device of the related art comprised of a semiconductor chip mounted on a circuit board, a capacitor has been mounted at the circuit by arranging a chip capacitor at the surface of the circuit board opposite to the surface mounting the semiconductor chip or arranging a chip capacitor in the vicinity of the semiconductor chip. This is so as to arrange the chip capacitor as close as possible to the connection terminal of the semiconductor chip and thereby reduce the inductance of the transmission path as much as possible.
The operating frequencies of semiconductor devices are becoming higher, however. If it becomes necessary to satisfy the condition of reducing the inductance value at the time of operation to not more than several pH, the problem arises that even with the method of arranging the chip capacitor at a position as close to the semiconductor chip as possible at the surface opposite to the position where the semiconductor chip is mounted, the inductance at the part connected with the electrode may end up exceeding the desired value depending on the thickness of the board or the size of the chip capacitor and the required performance of the semiconductor device will no longer be able to be obtained.